What Is a Speed Index?

Learn more about this important horse racing statistic.

Learn more about this important horse racing statistic.

A horse receives a speed index number every time he races at an AQHA-recognized track. Because each racetrack is different, race times vary a bit from track to track, and the speed index system was developed as a way to compare horses and races run at different tracks.

Without the SI rating system: Dash For Cash ran 440 yards in :21.17 seconds. (Uh huh. Is that good?) With the SI rating system: Dash For Cash earned a 114 SI in that race. (OK! 114 is fast!)

The SI number often is listed after a horse’s name, like Dash For Cash SI 114, and is the fastest speed index the horse ran during his career. The horse could have run that SI more than once (Easy Jet ran his top SI of 100 nine times), or it could have been a once-in-a-lifetime performance (Bully Bullion ran higher than 97 only once, earning a 104 SI). To find out how a particular horse fared on the track, take a look at his race record at Equineline.com.

How is a speed index figured?

Every year and for every racetrack, AQHA takes the three fastest times run at recognized distances in each of the preceding three years, and averages those nine numbers to find the time that represents an SI of 100 for that distance. Other speed index ratings for each distance are figured fractionally from the time that determined the SI 100.

Why not just pick the fastest times from around the country and use the same numbers for all tracks? Because track and atmospheric conditions vary from place to place, and that affects the way horses run. For instance, a :21.30 quarter-mile time earns a 100 SI at Ruidoso Downs in the mountains of New Mexico, but a :22.03 earns a 100 SI at Delta Downs in the Louisiana bayous.

How can I use speed indexes to judge a horse’s potential?

Keep in mind that speed index rating systems are based on times run by the very best runners at each track. SIs in the 70s are pretty good, 80s are getting speedy, 90s are down-right fast and 100+ are just plain awesome. When a horse runs an SI of 100, it’s like his GPA equals his class valedictorian’s. When it’s higher than 100, he’s the one that gets to give the valedictory address.

But don’t stop with just a horse’s speed index. Look at his repeat performances at certain distances. How fast a horse ran at different distances indicates whether he had quick speed or staying power.
When you’re looking for an arena prospect, whether a steer wrestling mount or barrel horse, you’re looking for a horse with quick speed, because he’ll only have to burn those jets for 50 to 100 yards. Check out his (or his sire’s or dam’s) race record to see if his lick was a quick trip or a long haul.

What can a horse’s race record tell me?

Race records can tell you race distances, track conditions and speed indexes, as well as a horse’s placings and margins of finish, for every race that horse ran during his career.

You can order detailed race records at equineline.com.

7 thoughts on “What Is a Speed Index?”

  1. Hi! How can you find out what your horses SI is??? I have a QH and he blows everyone I race him with (for fun) out of the water! Also, his sire has an SI of 101, so I’d really like to see how I can find out what his might be!

  2. Michelle,

    If your horse has a race record, the speed index will be on file with AQHA. Contact Customer Service at 806-376-4811 Monday-Friday from 8-5 CST to get the information you need.

  3. in a work out for 250 yards my mare ran it in 11 seconds. what is the speed index on this time

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